<template>
  <div class="camera_outer">
    <video
      id="videoCamera"
      :width="videoWidth"
      :height="videoHeight"
      autoplay
    ></video>
    <canvas
      id="canvasCamera"
      style="display:none;"
      :width="videoWidth"
      :height="videoHeight"
    ></canvas>
 
    <div
      v-if="imgSrc"
      class="img_bg_camera"
    >
      <img
        :src="imgSrc"
        alt=""
        class="tx_img"
      >
    </div>
    <button @click="getCompetence()">
      打开摄像头
    </button>
    <button @click="stopNavigator()">
      关闭摄像头
    </button>
    <button @click="setImage()">
      拍照
    </button>
  </div>
</template>
 <script>
 export default {
  data () {
   return {
    videoWidth: 3000,
    videoHeight: 300,
    imgSrc: '',
    thisCancas: null,
    thisContext: null,
    thisVideo: null,
   }
  },
  methods: {
// 调用权限（打开摄像头功能）
   getCompetence () {
    var _this = this
    this.thisCancas = document.getElementById('canvasCamera')
    this.thisContext = this.thisCancas.getContext('2d')
    this.thisVideo = document.getElementById('videoCamera')
    // 旧版本浏览器可能根本不支持mediaDevices，我们首先设置一个空对象
    if (navigator.mediaDevices === undefined) {
     navigator.mediaDevices = {}
    }
    // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
    // 使用getUserMedia，因为它会覆盖现有的属性。
    // 这里，如果缺少getUserMedia属性，就添加它。
    if (navigator.mediaDevices.getUserMedia === undefined) {
     navigator.mediaDevices.getUserMedia = function (constraints) {
      // 首先获取现存的getUserMedia(如果存在)
      var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.getUserMedia
      // 有些浏览器不支持，会返回错误信息
      // 保持接口一致
      if (!getUserMedia) {
       return Promise.reject(new Error('getUserMedia is not implemented in this browser'))
      }
      // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
      return new Promise(function (resolve, reject) {
       getUserMedia.call(navigator, constraints, resolve, reject)
      })
     }
    }
    var constraints = { audio: false, video: { width: this.videoWidth, height: this.videoHeight, transform: 'scaleX(-1)' } }
    navigator.mediaDevices.getUserMedia(constraints).then(function (stream) {
     // 旧的浏览器可能没有srcObject
     if ('srcObject' in _this.thisVideo) {
      _this.thisVideo.srcObject = stream
     } else {
      // 避免在新的浏览器中使用它，因为它正在被弃用。
      _this.thisVideo.src = window.URL.createObjectURL(stream)
     }
     _this.thisVideo.onloadedmetadata = function (e) {
      _this.thisVideo.play()
      console.log(e);
     }
    }).catch(err => {
     console.log(err)
    })
   },
// 绘制图片（拍照功能）
 
   setImage () {
    var _this = this
    // 点击，canvas画图
    _this.thisContext.drawImage(_this.thisVideo, 0, 0, _this.videoWidth, _this.videoHeight)
    // 获取图片base64链接
    var image = this.thisCancas.toDataURL('image/jpg')
    _this.imgSrc = image
    this.$emit('refreshDataList', this.imgSrc)
   },
// base64转文件
 
   dataURLtoFile (dataurl, filename) {
    var arr = dataurl.split(',')
    var mime = arr[0].match(/:(.*?);/)[1]
    var bstr = atob(arr[1])
    var n = bstr.length
    var u8arr = new Uint8Array(n)
    while (n--) {
     u8arr[n] = bstr.charCodeAt(n)
    }
    return new File([u8arr], filename, { type: mime })
   },
// 关闭摄像头
 
   stopNavigator () {
    this.thisVideo.srcObject.getTracks()[0].stop()
   }
  },
 
 }
  
 </script>
 <style lang="scss" scoped>
 .camera_outer{
  position: relative;
  overflow: hidden;
//   background: url("../../assets/img/user_0608_04.jpg") no-repeat center;
  background-size: 100%;
  video,canvas,.tx_img{
   -moz-transform:scaleX(-1);
   -webkit-transform:scaleX(-1);
   -o-transform:scaleX(-1);
   transform:scaleX(-1);
  }
  .btn_camera{
   position: absolute;
   bottom: 4px;
   left: 0;
   right: 0;
   height: 50px;
   background-color: rgba(0,0,0,0.3);
   line-height: 50px;
   text-align: center;
   color: #ffffff;
  }
  .bg_r_img{
   position: absolute;
   bottom: 0;
   left: 0;
   right: 0;
   top: 0;
  }
  .img_bg_camera{
   position: absolute;
   bottom: 0;
   left: 0;
   right: 0;
   top: 0;
   img{
    width: 100%;
    height: 100%;
   }
   .img_btn_camera{
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 50px;
    line-height: 50px;
    text-align: center;
    background-color: rgba(0,0,0,0.3);
    color: #ffffff;
    .loding_img{
     width: 50px;
     height: 50px;
    }
   }
  }
 }
 </style>